Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 2021 Nowhere to escape – Diversity and community composition of ferns and lycophytes on the highest mountain in Honduras Reyes-Chávez, Johan ; Quail, Megan ; Tarvin, Stephanie ; Kessler, Michael ; Batke, Sven P Abstract: IPCC predictions for Honduras indicate that temperature will increase by up to 3–6°C and precipitation will decrease by up to 7–13% by the year 2050. To better understand how fern and lyco- phyte communities might be affected by climate change, we comprehensively surveyed the community compositions of ferns and lycophytes at Celaque National Park, the highest mountain in Honduras. We surveyed a total of 80 20 × 20 m2 plots along an altitudinal gradient of 1249–2844 m a.s.l., identifying all species and estimating their abundances. We recorded a total of 11,098 individuals from 160 species and 61 genera. Community composition was strongly influenced by changes in altitude, precipitation and the abundance of bryophytes (a proxy for air humidity). Of the 160 species, 63 are expected, under a RCP2.6 scenario for the year 2050, to shift their range fully or partially above the maximum altitude of the mountain. Of these, 65.1% are epiphytes. We found that species with narrow altitudinal ranges at high altitudes were more at risk. Our study indicated that conservation efforts should prioritise higher altitudinal sites, focusing particularly on preserving the vulnerable epiphytic fern species, which are likely to be at greater risk. DOI: https://doi.org/10.1017/s0266467421000122 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-204461 Journal Article Published Version The following work is licensed under a Creative Commons: Attribution 4.0 International (CC BY 4.0) License. Originally published at: Reyes-Chávez, Johan; Quail, Megan; Tarvin, Stephanie; Kessler, Michael; Batke, Sven P (2021). Nowhere to escape – Diversity and community composition of ferns and lycophytes on the highest mountain in Honduras. Journal of Tropical Ecology, 37(2):72-81. DOI: https://doi.org/10.1017/s0266467421000122 Journal of Tropical Ecology Nowhere to escape – Diversity and community www.cambridge.org/tro composition of ferns and lycophytes on the highest mountain in Honduras 1,2 2 2 3 Research Article Johan Reyes-Chávez , Megan Quail , Stephanie Tarvin , Michael Kessler and Sven P. Batke1,2 Cite this article: Reyes-Chávez J, Quail M, Tarvin S, Kessler M, and Batke SP. Nowhere to 1 – Centro Zamorano de Biodiversidad, Departamento de Ambiente y Desarrollo, Escuela Agrícola Panamericana, escape Diversity and community composition 2 of ferns and lycophytes on the highest Francisco Morazán, Honduras; Biology Department, Edge Hill University, Ormskirk, L39 4QP, United Kingdom 3 mountain in Honduras. Journal of Tropical and Systematic and Evolutionary Botany, University of Zurich, 8008 Zurich, Switzerland Ecology https://doi.org/10.1017/ S0266467421000122 Abstract Received: 27 November 2020 IPCC predictions for Honduras indicate that temperature will increase by up to 3–6°C and pre- Revised: 6 April 2021 cipitation will decrease by up to 7–13% by the year 2050. To better understand how fern and Accepted: 10 May 2021 lycophyte communities might be affected by climate change, we comprehensively surveyed the Keywords: community compositions of ferns and lycophytes at Celaque National Park, the highest moun- 2 Altitudinal gradients; Celaque; Central America; tain in Honduras. We surveyed a total of 80 20 × 20 m plots along an altitudinal gradient of climate change; cloud forest; epiphytes; 1249–2844 m a.s.l., identifying all species and estimating their abundances. We recorded a total mid-elevation peak; species richness of 11,098 individuals from 160 species and 61 genera. Community composition was strongly Author for correspondence: influenced by changes in altitude, precipitation and the abundance of bryophytes (a proxy for Sven P. Batke, air humidity). Of the 160 species, 63 are expected, under a RCP2.6 scenario for the year 2050, to Email: [email protected] shift their range fully or partially above the maximum altitude of the mountain. Of these, 65.1% are epiphytes. We found that species with narrow altitudinal ranges at high altitudes were more at risk. Our study indicated that conservation efforts should prioritise higher altitudinal sites, focusing particularly on preserving the vulnerable epiphytic fern species, which are likely to be at greater risk. Introduction Mountains are ideally suited to study the effect of climate change on species distributions due to their rapid variability of climate over short altitudinal distances (Kessler et al. 2016; Rogora et al. 2018). In addition, these geographic features often harbour a very diverse and unique assemblage of fauna and flora and form regional biodiversity hotspots of high conservation importance (Lomolino 2001). Many of these species have discrete altitudinal distributions, determined partially by their biology and the historical distribution of each species, amongst other factors (Watkins et al. 2006). Current evidence suggests that plant species ranges have seen an average increase of approximately 30–36 m upwards along altitudinal gradients over the last 10 years, an affect that can be attributed to climate change (Jump et al. 2012; Lenoir et al. 2008; Morueta-Holme et al. 2015). Projections suggest that under a 1.5°C increase scenario, we can anticipate further upward shifts in altitude and a loss of >50% of the geographic range of 8% of plant species by the year 2030 (IPCC 2018). Tropical locations, in particular, are believed to show exacerbated effects of climate change on altitudinal distribution patterns, largely due to the narrow optimal temperature ranges of tropical species (Feeley & Silman 2010), with ben- eficial effects for some species and detrimental results for others (Gibson-Reinemer & Rahel 2015). Upslope shifts have potentially negative implications for future diversity, by increasing the risk of extinction for species that occupy high-altitude sites and that have a narrower range size (Colwell et al. 2008). As such, altitudinal distribution patterns have been studied for several dec- ades, with particular focus on tropical forest vegetation (Cardelus et al. 2006; Ibisch et al. 1996; © The Author(s) 2021. Published by Cambridge Kessler 2001; Kidane et al. 2019; Krömer et al. 2005; Rahbek 1995; Richards 1952; Wolf 1993; University Press. This is an Open Access article, Zhou et al. 2019). However, many Central and South American studies have mostly focused on distributed under the terms of the Creative countries such as Costa Rica (Stroud & Feeley 2017), whilst other areas, including Honduras, Commons Attribution licence (http:// creativecommons.org/licenses/by/4.0), which have been largely neglected, making generalisations on the effect of climate change on species permits unrestricted re-use, distribution and altitudinal distributions difficult. In particular, the limited attention that Honduras has received reproduction, provided the original article is has also been restricted to a small number of taxonomic groups. The greatest concentration of properly cited. these studies in Honduras has focused on birds (Jones et al. 2020; Neate-Clegg et al. 2018), with fewer studies investigating invertebrates (Anderson & Ashe 2000) and plants (Imbach et al. 2013). Ferns and lycophytes are especially vulnerable to increased temperatures and decreased pre- cipitation, which are both predicted under future climate change, and their responses to these Downloaded from https://www.cambridge.org/core. UZH Hauptbibliothek / Zentralbibliothek Zürich (Bill To for 21002 Zurich Uni), on 24 Jun 2021 at 06:57:56, subject to the Cambridge Core terms of use , available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0266467421000122 2 J Reyes-Chávez et al. Figure 1. Digital elevation model (DEM) of Celaque National Park. Points show the sample locations (n = 80). conditions will likely differ between terrestrial and epiphytic species To improve our understanding of fern community assemblages (Mandl et al. 2010). As a result, this climate sensitive, globally across the greatest altitudinal range in Honduras, in this study, we distributed and diverse group of plants has received substantial (1) investigated for the first time how species richness, diversity, attention in the literature on global altitudinal distribution and community composition patterns of ferns and lycophytes pattern studies; both directly (Kessler et al. 2001;Kluge&Kessler changes along an altitudinal gradient on the highest mountain 2011;Mandlet al. 2010;Watkinset al. 2006) and indirectly in Honduras, (2) tested whether there are differences within these (Sánchez-González et al. 2010). However, there is still a severe lack patterns between epiphytes and terrestrial species, (3) attempted to of available distribution data for ferns and lycophytes from some identify the underlying environmental factors that drive these pat- Central American countries such as Honduras, and there is terns, and (4) identified which species are likely to be at greater risk currently no specific distributional data available for epiphytic ferns under predicted changes in climate. It is hoped that the data from and lycophytes from anywhere in Honduras. For example, epiphytes this study can help us to better understand and generalise